2 Preface to the Fourth (2002) Edition
4 Plan 9 continues to grow and adapt.
5 The fourth major release of the system
6 incorporates a number of changes, but the most central
7 is the conversion to a new version of the 9P file system
9 This new version was motivated by a desire to support
10 files with name elements longer than 27 bytes (the old
12 but the opportunity was taken to change a number of other things
14 making it more efficient, more flexible, and easier to encapsulate.
15 One simple but indispensable new feature made possible by the protocol
16 change is that the system now records the user who last modified a file;
20 to identify the culprit.
22 Many aspects of system security have been improved.
23 The new security agent
25 maintains user passwords, while
27 keeps them safe and enables single sign-on to multiple domains and machines
28 using a variety of secure protocols and services.
30 Throughout the system, components have been rewritten and interfaces
31 modified to eliminate restrictions, improve performance, and clarify design.
32 The full list is too long to include here, but significant changes have occurred
33 in a number of system calls
46 (many pages in section 2, including
51 The changes are sweeping and are accompanied by many new programs, tools,
54 See the manual pages and the accompanying documents for more information.
60 Computing Science Research Center